1 | # @author Donnie Cameron (macnod)
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2 | # @url https://github.com/macnod/DcServer
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3 | # @readme http://donnieknows.com/blog/perl-sockets-swimming-thread-pool
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4 |
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5 | # One lurking issue with the ThreadPoolServer is that several threads don't get
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6 | # a chance to return before the server shuts down. In a perfect world they'd
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7 | # all get a chance to notice the 'stop' flag has been set and thusly
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8 | # stop. However, it is only by chance this happens as most will spend most of
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9 | # their lives either blocked listening to a socket (accept_requests) or blocked
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10 | # waiting to dequeue a message (request_handlers). Possible solutions, such as
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11 | # interupts, have problems of their own - interrupting mid-read of a socket
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12 | # could be bad. Since this is non-fatal, and non-trivial to fix, I'm just
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13 | # leaving it for now.
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14 |
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15 | package SocketsSwimmingThreadPoolServer;
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16 |
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17 | use lib '.';
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18 | use threads;
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19 | use threads::shared;
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20 | use Thread::Queue;
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21 | use IO::Socket;
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22 | use Time::HiRes qw/sleep/;
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23 | use strict;
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24 | use warnings;
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25 |
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26 | my $stop :shared;
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27 | my $accept_queue = Thread::Queue->new;
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28 | my $closed_queue = Thread::Queue->new;
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29 |
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30 | sub new {
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31 | # Params: host, port, thread_count, eom_marker, main_yield, main_cb,
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32 | # done_cb, processor_cb
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33 | my ($proto, %param)= @_;
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34 | my $class= ref($proto) || $proto;
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35 | bless +{
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36 | socket_defaults => +{
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37 | LocalHost => $param{host} || 'localhost',
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38 | LocalPort => $param{port} || 8191},
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39 | thread_count => $param{thread_count} || 10,
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40 | main_yield => $param{main_yield} || 1,
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41 | main_cb => $param{main_cb} || sub {},
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42 | done_cb => $param{done_cb} || sub {},
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43 | processor_cb => $param{processor_cb} || \&processor,
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44 | eom_marker => $param{eom_marker} || "\\n\\.\\n",
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45 | thread_pool => undef,
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46 | listen_queue => 5
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47 | } => $class;
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48 | }
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49 |
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50 | # This callback (for processor_cb) simply explains no other processor function
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51 | # defined.
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52 | sub processor
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53 | {
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54 | my ($data, $ip, $tid, $fnstop)= @_;
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55 | return "[tid=$tid; ip=$ip] No function implemented";
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56 | }
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57 |
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58 | sub start
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59 | {
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60 | my $self= shift;
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61 |
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62 | # Start a thread to dispatch incoming requests
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63 | threads->create(sub {$self->accept_requests})->detach;
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64 |
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65 | # Start the thread pool to handle dispatched requests
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66 | for (1 .. $self->{thread_count})
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67 | {
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68 | threads->create(sub {$self->request_handler})->detach;
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69 | }
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70 |
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71 | # Start a loop for performing tasks in the background, while
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72 | # handling requests
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73 | $self->main_loop;
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74 |
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75 | $self->{done_cb}->();
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76 | }
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77 |
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78 | sub stop
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79 | {
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80 | my $self = shift;
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81 | $stop= 1;
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82 | }
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83 |
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84 | sub main_loop
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85 | {
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86 | my $self = shift;
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87 | my $counter = 1;
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88 | until($stop)
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89 | {
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90 | $self->{main_cb}->($counter++, sub {$self->stop});
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91 | sleep $self->{main_yield};
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92 | }
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93 | }
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94 |
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95 | sub accept_requests
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96 | {
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97 | my $self = shift;
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98 | my %socket;
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99 | # lsocket => listerner [sic] socket
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100 | my $lsocket;
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101 | while (!defined $lsocket || !$lsocket)
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102 | {
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103 | $lsocket = new IO::Socket::INET(%{$self->{socket_defaults}}, Proto => 'tcp', Listen => 1, Reuse => 1);
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104 | if (!defined $lsocket || !$lsocket)
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105 | {
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106 | print STDERR "Warning! Can't create listener socket so server can't start (trying again in 1 second).\n";
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107 | print STDERR "Error message: \"" . $! . "\"\n\n";
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108 | sleep(1);
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109 | }
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110 | }
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111 | until($stop)
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112 | {
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113 | # csocket => connected socket (for doing the actual communications)
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114 | my $csocket = $lsocket->accept;
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115 | my $n = fileno $csocket;
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116 | $socket{$n} = $csocket;
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117 | # add this to the queue that a virtual horde of request_handlers are
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118 | # waiting upon (much like vultures)
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119 | $accept_queue->enqueue($n . ' ' . inet_ntoa($csocket->peeraddr));
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120 | # we then go ahead and destroy any sockets that we are no longer using.
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121 | # Note the use on a non-blocking dequeue (so it returns straight away) and
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122 | # that $n may be undefined (if the queue is empty) skipping the while loop
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123 | # altogether
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124 | while($n = $closed_queue->dequeue_nb)
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125 | {
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126 | # note: 2 = finished both reading and writing to this socket
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127 | $socket{$n}->shutdown(2);
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128 | delete $socket{$n}
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129 | }
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130 | }
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131 | # note: 2 = finished both reading and writing to this socket
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132 | $lsocket->shutdown(2);
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133 | }
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134 |
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135 | # @function request_handler()
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136 | #
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137 | # There are *thread_count* request_handler threads all sitting, waiting, to
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138 | # process any incoming requests received via the socket. Note that the whole
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139 | # 'race for data' issue is being handled by the Thread::Queue->dequeue command
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140 | # which is, according to the documentation, thread safe. I presume the actual
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141 | # dequeuing is somehow synchronized.
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142 | sub request_handler
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143 | {
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144 | my $self= shift;
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145 | my ($n, $ip, $data);
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146 | my ($receive_time, $process_time, $send_time);
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147 | until($stop)
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148 | {
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149 | # note: dequeue is blocking so this thread will wait here until something
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150 | # is enqueued
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151 | ($n, $ip)= split / /, $accept_queue->dequeue();
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152 | next unless $n;
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153 | # open socket for reading and writing... reading first of course
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154 | open my $socket, '+<&=' . $n or die $!;
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155 | # this will read in the payload from the socket until the end of message
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156 | # sentinel value is detected. Note that this is done in a loop, so the
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157 | # client side of the socket may send multiple requests. Eventually the
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158 | # client will close their end of the socket causing the data to be
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159 | # undefined (maybe - I don't quite understand the defining construct - see
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160 | # below) and breaking out of the loop.
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161 | if(defined($data = $self->receive_client_request($socket)))
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162 | {
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163 | # we then pass the payload to the registered processor function (provided
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164 | # by the caller) to do the actual legwork, the result of which is written
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165 | # back to the socket.
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166 | my $result = $self->{processor_cb}->($data, $ip, threads->tid, sub {$self->stop});
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167 | print $socket $result, "\n.\n";
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168 | }
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169 | # this is where the socket is closed... so why am I eventually hitting a
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170 | # "cannot assign address" problem?
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171 | close $socket;
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172 | # add this socket number to the list of sockets to be destroyed
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173 | $closed_queue->enqueue($n);
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174 | }
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175 | }
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176 |
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177 | sub receive_client_request
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178 | {
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179 | my ($self, $socket)= @_;
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180 | # how does this construct work? eom_marker is a scalar (a string) so how can
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181 | # it be assigned to an anonymous array?
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182 | my ($eom, $buffer, $data)= $self->{eom_marker};
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183 | while ($buffer = <$socket>)
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184 | {
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185 | $data .= $buffer;
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186 | last if $data =~ s/$eom$//;
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187 | }
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188 | return $data;
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189 | }
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190 |
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191 | 1;
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